Exocytosis provides the membrane for protrusion, at least in migrating fibroblasts.
Bretscher
Mark S
MS
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D004705:Endocytosis; D005089:Exocytosis; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans